Electrical selector circuit arrangements



April 9, 1963 B. J. WARMAN ETAL 3,085,162

ELECTRICAL SELECTOR CIRCUIT ARRANGEMENTS Filed Nov. 27, 1959 sSheets-Sheet 1 CUPW swam INVENTORS BLOOMFIELD JAMES WARMAN WILLIAMBERNARD DELLER April 9, 1963 B, J. WARMAN ETAL 3,08

ELECTRICAL SELECTOR cmcurr ARRANGEMENTS Filed Nov. 27, 1959 '5Sheets-Sheet 2 DPVE 1 DIP/V52 DP/VE 1] l DP/VE 2 INVENTORS BLOOMFIELDJAMES WARIMN WILLIAM BERNARD HELLER April 9, 1963 a. J. WARMAN ETAL3,085,162

ELECTRICAL SELECTOR CIRCUIT ARRANGEMENTS Filed Nov. 27. 1959 3Sheets-Sheet 3 CURRENT DRWE STEERING PULSE Y 'E DRIVE 1 PULSE 1! 1cumzam' 5155mm 1 x EARTH 1 T l EARTH L i i i' z EBTL- i BLOOMFIELD JAMESVIARMAN WILUAM BERNARD HELLER BY unc -m United States Patent 3,985,162ELECTRICAL SELECTOR CIRCUIT ARRANGEMENTS Bloomfield James Warman,Charlton, London, and William Bernard Deller, Mottingham, London,England, assignors to Associated Electrical industries (Woolrich)Limited, London, England, a British company Filed Nov. 27, 1959, Ser.No. 355,715 Claims priority, application Great Britain Nov. 28, 1953 3Claims. (Cl. Shh-8) This invention relates to electrical selectorcircuit arrangements.

It is applicable both to circuits for random selection and also tocyclic switching circuits. Circuits employing electro-magnetic relays orelectronic discharge tubes are well known for this purpose. However,such arrange ments employ apparatus which is comparatively bulky andrequires appreciable power for actuating when employed for purposes suchas computers.

The main object of the invention is to provide improved apparatusemploying miniature components which is capable of high speed operation.

According to the present invention a selector switching circuitarrangement comprises a plurality of two-state magnetic cores eachcontrolling an associated load circuit and each core having a setwinding, a drive winding and a current steering winding, whereof each ofthe current steering windings is on one side connected to a currentsteering terminal and on the other side connected to the emitter of acommon base transistor having its collector connected to the associatedload and the arrangement being such that it a selected core is set,then, when a pulse is applied to the drive windings the selected coreonly will be re-set thereby inducing an in its current steering coilwhich is in the forward direction of the associated transistor emitterbase junction and so that the end remote from the emitter base junctionwill be negative to earth, which end is connected to the currentsteering coil circuits of the other cores, whereby if a current steeringpulse is then applied within the duration of the drive pulse currentwill flow in the current steering winding of a selected core only andhence in the associated load only.

The term load" is intended to include any suitable apparatus which maybe current or voltage operated and includes static or dynamic means forsupplying information only. The term terminal" is also intended in abroad sense to include any common connection. The term two-state coreimplies a magnetic core capable of assuming either one of two stablestates of opposite polarity magnetism.

An important application of the invention is to a cyclic circuit inwhich case the cores would be arranged in two groups each with its owndrive source and the two drives will be operated alternately so thatfirst a core of one group and then a core of the other group will besuccessively operated.

In order that the invention may be more clearly understood referencewill now be made to the accompanying drawings, in which:

FIG. 1 shows a selector circuit employing current steering.

FIG. 2 shows a cyclic counting circuit employing the same principle.

FIG. 3 illustrates graphically the operation of the circuit of FIG. 2.

FIG. 4 shows a circuit for applying current steering pulses in thearrangement of FIG. 1 or FIG. 2, and

FIG. 5 illustrates graphically the voltage changes which occur in thecircuit of FIG. 4.

3,085,162 Patented Apr. 9, 1963 "ice In FIG. 1 there are shown threetwo-state cores A, B and C of the kind having two stable magnetic statesof opposite polarity, i.e. a set state and a re-set state. Each of thecores has a set winding a, a current steering winding [1 and a drivewinding 0. The set windings a are controlled from a suitable selectorarrangement so arranged that the set winding of any selected core may beenergised. The current steering windings b of the cores are, at theirleft hand ends, connected to the current steering terminal and at theirright hand ends are connected to the emitters of their associated commonbase transistors, the collector circuit of which transistors areconnected to loads indicated by the references RA, RB and RCrespectively. These may either be current actuated or, in some cases, avoltage pulse may be derived from terminals PA, PB or PC, as indicatedin dotted lines.

it will be appreciated that only one of the cores will be set at any onetime. Assume for purposes of explanatlon that the core A is selected andhas been set by a current through its set winding a. If now apositivegoing pulse is applied to the drive terminal the core A will bere-set, the remaining cores being unafiected. The re-sctting of core Awill induce an E.M.F. in the current steering winding 11 which is in theforward direction of the emitter circuit of transistor T2, i.e. so thatthe left end of the winding will tend to have a negative potentialrelative to the right hand end. The negative potential developed at theleft end of winding b will be applied to the common drive terminal andhence through all the other current steering windings to the emitters oftheir associated transistors and this will tend to hold them cut oil.

It now, during the drive pulse a positive going pulse is applied to thecurrent steering terminal this would constitutc an EM. F. in series withthe induced in the winding [2 of core A so that the common pointconnested with the current steering terminal will tend to remainnegative relative to earth and this negative potential will, as aboveexplained, he applied to the emitters of TB and TC. The net result willbe that current will pass to earth through the low impedance winding bof core A and the low impedance emitter-base circuit of TA but will notflow through the other current steering windings. This will in turncause current to flow through the collector circuit and the load RA. Thecollector circuit will in contradislinction to the emitter have a highimpedance to earth. it will be appreciated that the Ell LP. developedacross the current steering winding b and the negative potential appliedto the other current steering circuits will not be allected byconditions in the load circuit RA since this will be isolated from thecurrent steering winding by the transistor.

It will be appreciated that the positive end of current steering windingb should be connected to a circuit having a low impedance to earth whenpassing current and also it should not be effected by conditions in theload circuit. The transistor satisfies these requirements to anappreciable extent.

It will also be appreciated that the drive pulse should be applied so asto commence before the current steering pulse so that the E.M.F. acrossthe current steering winding of a selected core is already present whenthe drive pulse is applied. Preferably also the external currentsteering circuit (not shown) includes an appreciable resistance.

As above mentioned, the selection of the cores may be effected in anysuitable manner and there may be either random selection or cyclicselection.

FIG. 2 shows the invention applied to a cyclic counting circuit.

In the arrangement shown there are six load circuits R1R6 which areactuated in sequence. Each of the load circuits is actuated by anassociated two state drive core indicated by the references I-VI. Eachof the drive cores is shown with a set winding (1, current steeringwinding b and drive winding 0 whilst in addition there is a primingwinding d. It will be observed that the cores are arranged in twogroups, the cores I, III and V are arranged in the first group and alltheir drive windings c are connected to the first Drive 1. Similarly,the cores II, IV and VI are arranged in a second group and their drivewindings c are driven from Drive 2. At the same time all the currentsteering windings are connected to a common drive source, indicated asDrive 3. In the drawing there are two drive 3 terminals shown; this ispurely to simplify the drawing and in actual practice both ter minalswould be commoned.

In order to understand the operation of the circuit, it will be assumedthat initially the core I has been set by means of the priming windingd, the remaining cores being in the re-set" state. It now a pulse ispassed through Drive 1, core I will be re-set. This will induce anE.M.F. across its steering winding b in such a direction that the lefthand end tends to be negative with respect to the right hand end, i.e.it will be in the forward direction of the emitter circuit of T2 but atthe same time the negative potential at the left end of the winding willbe applied to all the other current steering windings and will tend toback them oil? so that if new a positive going pulse is applied throughDrive 3 current will pass through the winding 1) of core I only and willbe held off from passing through the other current steering windings ofthe other cores.

The developed across winding b of core I will render the transistor T2conductive and cause current to flow through the set winding a of thecore II and at the same time it will apply a pulse to the load circuitR2.

As explained in connection with FIG. 1. the right hand end of thecurrent steering winding b, i.e. the positive end, is clamped to earththrough a low impedance which is unaffected by the current through thecollector circuit and the load R2 and, therefore, a relatively highnegative potential can be developed at the left hand which backs off theother current steering windings and prevents current flowing throughthem when a current pulse from Drive 3 is applied to them. Furthermore,the voltage developed across the winding [2 is independent of thevoltage developed across R2 due to current flow through the collectorcircuit of T2. Hence, the backing off of the other transistors is in noway impaired by the voltage developed across the load circuit R2.

This feature is of considerable importance since it ensures accuracy ofoperation of the circuit and permits appreciable output load signals tobe obtained whilst at the same time avoiding faulty operation due toinadequate backing off of the unwanted cores.

Reverting to the sequence of operations the current flowing through thewinding a of the core II and load circuit R2 will set the core II sothat when a pulse is now applied through Drive 2 the core II will bere-set. This in turn will cause a current pulse to pass through currentsteering winding b of core II and hence by way of transistor T3 to setthe core III and pass a pulse through load circuit R3. The next pulsefrom Drive 1 will now re-set core III and set the core IV. Eventually,when core VI is re-set this will once again set the core I, it beingappreciated that the points marked X indicate a common point, theintervening connections being omitted for the purpose of simplifying thedrawing.

FIG. 3 shows the sequence of operations graphically and it will beobserved that positive pulses are applied to Drive 1 and Drive 2alternately. The pulses applied to Drive 3 occur simultaneously to Drive2 pulses. However, the Drive 3 pulses are shorter in duration than theCit 2' Drive 1 and Drive 2 pulses and start later and terminate earlierthan the Drive 1 and Drive 2 pulses.

Whilst in FIG. 1 there are shown only three load circuits and in FIG. 2only six load circuits these are by way of example only as clearly theremay be any suitable number of load circuits.

In some cases provision may be made for adjusting the timing of theDrive 3 steering pulses (FIG. 3) relative to the Drive 1 and Drive 2pulses.

FIG. 4 shows a circuit for applying the current steering pulses. Thiscircuit essentially comprises a current steering transistor TCS theoutput of which is connected through a resistor R with the currentsteering line.

In FIG. 4 it is intended to show the current steering pulses applied tothe circuit of FIG. 1 and the connections to core A only are shown. FIG.4 is, of course, also applicable to FIG. 2.

FIG. 5 shows graphically the voltage changes occurring in the circuit ofFIG. 1. Initially at time 1 a positive going drive pulse is applied;this is effective to reverse the core A and induce an EMF. in the coil12. Shortly afterwards at time r a negative going pulse is applied tothe base of current steering transistor TCS. This produces a largepositive going voltage pulse at the point X and a voltage pulse ofreduced amplitude at Y. At the point Z, i.e. at the emitter oftransistor TA, a small positive going voltage step occurs at time t; andthen a large voltage pulse at 1 What we claim is:

1. An electrical selector circuit arrangement comprising a plurality oftwo-state magnetic cores, an associated load circuit controlled by eachcore and each core having a set winding, a drive winding and a currentsteering winding, each of said current steering windings being on oneside connected to a current steering terminal and on the other sideconnected to the emitter of an associated transistor having its basegrounded and its collector connected to the associated load, meanswhereby if a selected core is set, when a pulse is applied to the drivewindings the selected core only will be re-set thereby inducing in itscurrent steering coil an EMF. which is in the forward direction of theassociated transistor emitter-base junction, and means for applying acurrent steering pulse to the current steering windings applied withinthe duration of the drive pulse, current will flow in the currentsteering winding of a selected core only and hence in the associatedload only.

2. An electric selector circuit arrangement comprising a plurality oftwo-state magnetic cores arranged in two groups adapted for sequentialoperation, in a sequence in which cores in one group alternate withcores in the other group, each core having a setting winding, a drivewinding and a current steering winding, an associated transistorconnected to each of said current steering windings and driving arespective load circuit, a connection between each load circuit and thesetting winding of the core in the alternate group next to operate inthe sequence, means for applying re-setting currents to all the drivewindings of the two groups alternately and means for concurrentlyapplying current steering pulses to all the current steering windings sothat a current steering pulse flows only in the current steering windingand associated transistor of a core which is being reset.

3. An electric selector circuit arrangement comprising a plurality oftwo-state magnetic cores arranged in two groups adapted for sequentialoperation in a sequence in which cores in one group alternate with coresin the other group, each core having a setting winding, a drive windingand a current steering winding, an associated transistor connected toeach of said current steering windings and driving a respective loadcircuit, a connection between each load circuit and the setting windingof the core in the alternate group next to operate in the sequence,means for applying rc-setting currents to all the drive windings of thetwo groups alternately and a current steering circuit including atransistor adapted to apply current steering pulses through a resistorto all the current steering windings concurrently with the re-settingcurrent so that a current steering pulse flows only in the currentsteering winding and associated transistor of a 5 core which is beingreset.

References Cited in the file of this patent UNITED STATES PATENTSLawrence Feb. 2,

3. AN ELECTRIC SELECTOR CIRCUIT ARRANGEMENT COMPRISING A PLURALITY OFTWO-STATE MAGNETIC CORES ARRANGED IN TWO GROUPS ADAPTED FOR SEQUENTIALOPERATION IN SEQUENCE IN WHICH CORES IN ONE GROUP ALTERNATE WITH CORESIN THE OTHER GROUP, EACH CORE HAVING A SETTING WINDING, A DRIVE WINDINGAND A CURRENT STEERING WINDING, AN ASSOCIATED TRANSISTOR CONNECTED TOEACH OF SAID CURRENT STEERING WINDINGS AND DRIVING A RESPECTIVE LOADCIRUIT, A CONNECTION BETWEEN EACH LOAD CIRCUIT AND THE SETTING WINDINGOF THE CORE IN THE ALTERNATE GROUP NEXT TO OPERATE IN THE SEQUENCE,MEANS FOR APPLYING RE-SETTING CURRENTS TO ALL THE DRIVE WINDINGS OF THETWO GROUPS ALTERNATELY AND A CURRENT STEERING CIRCUIT INCLUDING ATRANSISTOR ADAPTED TO APPLY CURRENT STEERING PULSES THROUGH A RESISTORTO ALL THE CURRENT STEERING WINDINGS CONCURRENTLY WITH THE RE-SETTINGCURRENT SO THAT A CURRENT STEERING PULSE FLOWS ONLY IN THE